When studying the population dynamics of northwest England for our earlier book Human Demography and Disease (also published by Cambridge University Press) we became interested in the biology of the plagues that beset Europe after the Black Death. A plague struck this part of England and spread rapidly in 1597–98 and it was obvious from a basic training in zoology that this was not an outbreak of bubonic plague. By making a full family reconstitution study of the community at Penrith in Cumbria (where some 40% of the population died) it was possible to trace the spread of the disease between named individuals in the same family and between households. From this starting-point, we have made an interdisciplinary study of the epidemiology and biology of the plagues that have afflicted western Europe, concentrating on the outbreaks from the Black Death, which began in 1347, to the Great Plague of London. We have combined modern epidemiological concepts, computer modelling of epidemics, recent molecular biology studies, spatial analysis techniques, time-series analysis of the epidemics and the careful analysis of the sequence of infections in selected epidemics. We hope that our monograph will be of interest to a wide variety of readers who will come to look at historical plagues with different eyes.

Once again we thank Dr S. R. Duncan, of the University of Oxford, for introducing us to the intricacies of time-series analysis and for developing the mathematical models that we have used.